Introduction & Objective Prolieve® transurethral thermodilatation (TUTD) is the only third-generation transurethral microwave thermotherapy (TUMT) device that incorporates balloon dilation/compression of the prostatic urethra with cooled TUMT, at ≤50W power. We evaluated its 5-year efficacy in the treatment of symptomatic benign prostatic hyperplasia (BPH) in an open-label prospective multi-center trial. Methods Eligible patients with AUA symptom score (AUASS) ≥ 9, peak urine flow rate (Qmax) <12 ml/s, and prostate size 20-80 g without obstructing median lobe anatomy were enrolled. Prolieve® TUTD was delivered in the office setting under local anesthesia. AUASS, Quality of Life (QOL), BPH impact index (BPHII), Qmax and other measures were assessed at baseline, and at least annually thereafter to year 5. Adverse events (AEs) were recorded. Treatment success over time was analyzed using the Kaplan-Meier method while changes from baseline were evaluated using paired t-tests. Results Intention to treat (ITT) population was 225, of whom 220 with a mean (SD) age of 65 (5.9). completed treatment. 187/220 (85%) did not require urethral catheterization. AUAS, QOL and BPHII scores significantly improved from baseline in ≤ 3 months, with sustained improvements to year 5. Qmax also significantly improved from baseline at each annual follow up evaluation. Cumulative 5-year surgical retreatment rate was 14.2% (95% CI 9.5-20.8%). Transient urinary urgency and dysuria were the most commonly reported AEs. Conclusions Prolieve® TUTD is a safe and effective treatment option for BPH, with durable long-term improvements in voiding subjective symptoms and urinary flow rates. It is deliverable in the office setting and has a low catheterization rate and sexual side effects are rare.